The spores (conidia) are dark brown and usually occur in grape-like masses on white woolly colonies. The spores are flattened and have a colourless line at the edge. When germinating they break along the line in the manner of a clam shell. In some species the filaments have dark cross-walls. Common on dead plants, especially grasses and sedges, and often isolated from air near grassy places in the autumn. The photographs at the top of the page represent A. phaeospermum, a species commonly isolated in the laboratory from a variety of sorces. The strain in these pictures appeared as an air contaminant in a petri dish. The photos below are of Arthrinium cuspidatum found growing on dead grass stems in a salt marsh near St. Andrews, New Brunswick. The drawing illustrates several species.
Classification: Apiosporaceae (Sordariomycetidae). Holomorphs: Apiospora, Physalospora, Pseudoguignardia. Ref: Ellis 1971